Past volcanic eruptions triggered abrupt melting events on ancient ice sheets, according to an article published in Nature Communications this week. The findings imply the deposition of ash on ice surfaces could result in an increase in the contribution of ice sheet melt water to global sea level rise.
Although volcanic eruptions and the emission of ash into the atmosphere generally has a cooling effect on climate, little is known about the impact of volcanic activity on past ice sheets. Understanding the response of ice sheets to such forcing is important to fully comprehend the potential contribution of ice sheet melt to rising sea levels.
Francesco Muschitiello and colleagues shed light on this problem through the precise comparison of annually resolved Swedish lake sediments and Greenland ice from 13,000 years ago, during the last deglaciation period. The sediments record melt events on the Fennoscandian Ice Sheet that correspond strikingly with evidence for past explosive and sulfur-rich volcanic activity recorded in the ice between 13,000-12,000 years ago. Icelandic volcanic activity during the last deglaciation was 50 times greater than today. The authors conclude that this volcanic activity was likely responsible for these melting events through the deposition of dark ash on the bright ice surface, which absorbed more heat and encouraged the ice to melt.